The present invention relates to an image forming system composed of an image forming apparatus connected with a finisher for conducting such processing as punching, folding, stapling and shifting.
An image forming system connected with a finisher for conducting such processing as punching, folding, stapling and shifting to sheet with an image formed thereon is widely used as a system configured on the basis of a high speed image forming apparatus such as an image forming apparatus based on electrophotographic technology.
In the finisher, processing such as folding and stapling is carried out to sheet, which is temporarily stopped. Accordingly, to prevent collision of the sheets of paper conveyed one after another, the conveyance speed is increased immediately before and after a processing station, thereby ensuring a wide space between sheets of paper (Official Gazette of Japanese Patent Tokkaihei 5-16569). When such control is used, a sensor is installed at the sheet inlet of the finisher, the conveyance speed is increased based on the signal for detecting the trailing edge of the traveling sheet.
To ensure multiple types of finishing, an image forming system equipped with a plurality of finishers is proposed (Official Gazette of Japanese Patent Tokkai 2002-59496 and 2002-137503). In such an image forming system equipped with the plurality of finishers, not much consideration is given to the operation stability and efficiency in the management of the sheet conveyance speed as the overall image forming system.
When designing an image forming system equipped with a plurality of finishers, control will become complicated if each finisher is provided with the conveyance speed control function as in Official Gazette of Japanese Patent Tokkaihei 5-16569, and sheet conveyance control is separately carried out. Such a trouble as jamming is likely to occur and finishing efficiency is reduced, with the result that the efficiency of the overall image forming system will be deteriorated.
Official Gazette of Japanese Patent Tokkaihei 11-301920 discloses an image forming system provided with a finisher where finishing designation information and the information on the sheet attributes are sent from the image forming apparatus to the finisher where finishing is performed. However, such information is not sufficient for effective sheet conveyance control in the finisher and high speed processing in the finisher. For this purpose, it is necessary to capture information on the sheet conveyance speed and sheet ejection timing at the sheet ejection port of the finisher in the preceding step, namely, the finisher of the preceding step in an image forming apparatus and a plurality of finishers. Such information must be obtained in the finisher of the succeeding stage.
In the prior art, this type of information has been created in the finisher of the succeeding stage by allowing the model of the preceding apparatus to be identified by the succeeding model.
The control of this conveyance will be explained with reference to FIG. 1.
Timing of ejecting of sheet P and ejection conveyance speed H from the finisher Ml of the preceding stage are obtained from the rotation speed of the ejection roller R and distance D between the ejection sensor S and ejection port. Based on the aforementioned information, the finisher M2 of the succeeding stage performs various conveyance control.
In the prior art, the aforementioned information has been created in the finisher of the succeeding stage by allowing the model of the preceding apparatus to be identified by the succeeding model, as described above. To put it another way, if the model of the apparatus in the preceding stage is identified, the sensor distance D in the apparatus of the preceding stage and sheet ejection conveyance speed H in various operation modes of the model can be obtained. Thus, the finisher of the succeeding stage is provided with a table showing the correspondence between the model of the finisher of the preceding stage, sensor distance D and ejection conveyance speed H in various operation modes.
However, when there is an addition of a new function resulting from improvement of the finisher or modification of the ejection conveyance speed, or when a new model is connected as the finisher of the preceding stage, this table must be rewritten. For this purpose, the model must be changed due to the relationship with other finisher although there is no change in the function of the finisher. Even if there is no change of the model, table rewriting service is required. This raises the problem of increased servicing loads.